This hike is on unofficial trails or no trail at all in Ignacio Valley Open Space Preserve. Thunderbird Ridge is a subridge that starts at Thunderbird Court off of Fairway Drive in Novato, and rises up to Big Rock Ridge fire road at about 1400 feet. This hike starts out hugging the side of the ridge until we climb up to its spine and meet the unofficial Thunderbird Ridge Trail. We take this trail up the ridge until we meet the Pensacola Creek Trail, which drops a short distance down to Pensacola Creek, which is dry except during the rainy season. There the trail ends and we take the creek bed down a short distance when we start climbing up the ridge on the left until we reach the Piping Rock Ridge Trail. We take this trail up the steep ridge until we hit Big Rock Ridge Fire Road. We turn left and walk down then up until we reach the beginning of the Thunderbird Ridge Trail which we take all the way down back to Thunderbird Drive.